scholarly journals Accurate ab initio ro-vibronic spectroscopy of the X̃2Π CCN radical using explicitly correlated methods

2011 ◽  
Vol 135 (14) ◽  
pp. 144309 ◽  
Author(s):  
J. Grant Hill ◽  
Alexander Mitrushchenkov ◽  
Kazim E. Yousaf ◽  
Kirk A. Peterson
Keyword(s):  
Ab Initio ◽  
Explicitly Correlated ◽  
Explicitly Correlated Methods

scholarly journals The S66 Non-Covalent Interactions Benchmark Reconsidered Using Explicitly Correlated Methods Near the Basis Set Limit

2018 ◽  
Vol 71 (4) ◽  
pp. 238 ◽  
Author(s):  
Manoj K. Kesharwani ◽  
Amir Karton ◽  
Nitai Sylvetsky ◽  
Jan M. L. Martin
Keyword(s):  
Computational Cost ◽  
The Other ◽  
Basis Set ◽  
Basis Sets ◽  
Explicitly Correlated ◽  
Non Covalent Interactions ◽  
Explicitly Correlated Methods ◽  
The One ◽  
High Level ◽  
Covalent Interactions

The S66 benchmark for non-covalent interactions has been re-evaluated using explicitly correlated methods with basis sets near the one-particle basis set limit. It is found that post-MP2 ‘high-level corrections’ are treated adequately well using a combination of CCSD(F12*) with (aug-)cc-pVTZ-F12 basis sets on the one hand, and (T) extrapolated from conventional CCSD(T)/heavy-aug-cc-pV{D,T}Z on the other hand. Implications for earlier benchmarks on the larger S66×8 problem set in particular, and for accurate calculations on non-covalent interactions in general, are discussed. At a slight cost in accuracy, (T) can be considerably accelerated by using sano-V{D,T}Z+ basis sets, whereas half-counterpoise CCSD(F12*)(T)/cc-pVDZ-F12 offers the best compromise between accuracy and computational cost.

scholarly journals EXPANSION FORMULAE FOR ONE- AND TWO-CENTER CHARGE DENSITIES OVER COMPLETE ORTHONORMAL SETS OF EXPONENTIAL TYPE ORBITALS AND THEIR USE IN EVALUATION OF MULTICENTER–MULTIELECTRON INTEGRALS

2009 ◽  
Vol 08 (04) ◽  
pp. 597-602 ◽  
Author(s):  
I. I. GUSEINOV
Keyword(s):  
Exponential Type ◽  
Overlap Integrals ◽  
Charge Densities ◽  
Hartree Fock ◽  
Expansion Formulae ◽  
Multicenter Multielectron Integrals ◽  
Explicitly Correlated ◽  
Explicitly Correlated Methods ◽  
Exponential Type Orbitals ◽  
The One

The series expansion formulae are established for the one- and two-center charge densities over complete orthonormal sets of Ψα-exponential type orbitals (Ψα-ETO α = 1,0,-1,-2,…) introduced by the author. Three-center overlap integrals of Ψα appearing in these relations are expressed through the two-center overlap integrals between Ψα-orbitals. The general formulae obtained for the charge densities are utilized for the evaluation of arbitrary multicenter–multielectron integrals occurring when the complete orthonormal sets of Ψα-ETO are used as basis functions in the Hartree–Fock–Roothaan and explicitly correlated methods. The relationships for charge densities and multicenter–multielectron integrals obtained are valid for the arbitrary quantum numbers, screening constants, and location of Ψα-orbitals.

Optimized auxiliary basis sets for explicitly correlated methods

2008 ◽  
Vol 129 (18) ◽  
pp. 184108 ◽  
Author(s):  
Kazim E. Yousaf ◽  
Kirk A. Peterson
Keyword(s):  
Basis Sets ◽  
Explicitly Correlated ◽  
Explicitly Correlated Methods

scholarly journals Rethinking the X− + CH3Y [X = OH, SH, CN, NH2, PH2; Y = F, Cl, Br, I] SN2 reactions

2019 ◽  
Vol 21 (15) ◽  
pp. 7924-7931 ◽  
Author(s):  
Domonkos A. Tasi ◽  
Zita Fábián ◽  
Gábor Czakó
Keyword(s):  
Ab Initio ◽  
Sn2 Reactions ◽  
Explicitly Correlated ◽  
Leaving Groups

Explicitly-correlated ab initio computations reveal novel inversion and retention pathways for several SN2 reactions with different nucleophiles and leaving groups.

scholarly journals Toward a W4-F12 approach: Can explicitly correlated and orbital-based ab initio CCSD(T) limits be reconciled?

2016 ◽  
Vol 144 (21) ◽  
pp. 214101 ◽  
Author(s):  
Nitai Sylvetsky ◽  
Kirk A. Peterson ◽  
Amir Karton ◽  
Jan M. L. Martin
Keyword(s):  
Ab Initio ◽  
Explicitly Correlated
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